sea anemone

(Zool.) Any one of numerous species of soft-bodied Anthozoa, belonging to the order Actinaria; an actinian. [ 1913 Webster ]

☞ They have the oral disk surrounded by one or more circles of simple tapering tentacles, which are often very numerous, and when expanded somewhat resemble the petals of flowers, with colors varied and often very beautiful. [ 1913 Webster ]